A printing head for an ink jet printer with an exchangeable ink cartridge is specified in EP-A-402 241 as follows: On the base plate of the printing head, the jet plate is arranged on the one side and a holder for the ink cartridge on the opposite side. The cartridge contains a foam element that is impregnated with ink. On the side facing the base plate, the bottom of the casing of the cartridge has a hollow space that is sealed against the outside by a rubber plug and delimited against the foam element by a sieve. A needle projects from the base plate; the capillary of said needle communicates with the ink ducts of the jet plate by way of hollow spaces. When the cartridge is inserted, the rubber plug is pierced with the needle. The point of the latter then projects into the hollow space. The cover on the opposite side of the casing has a venting aperture that feeds into another hollow space. For a trouble-free operation, this solution requires that the first-mentioned hollow space always remains filled with ink, which, however, cannot be guaranteed particularly near the end of the ink supply.